odd things are happening with my engine temps
- Thread starter 1396midget
- Start date
1396midget
Well-Known Member
Hello again 
It's still doing it.
New water pump.
New radiator.
New temp sender.
New stat.
New hoses all round.
Heater is fin, good and warm.
Very strange.
Any other suggestions? Still exhibiting dame symptoms of overheating when driven at steady motorway speeds.
No overheating if thrashed hugely on back roads. ( many revs many gearshifts etc) Starting to wonder if there's an airflow issue (e.g all air stalled in engine bay at higher speeds) or something
It's still doing it.
New water pump.
New radiator.
New temp sender.
New stat.
New hoses all round.
Heater is fin, good and warm.
Very strange.
Any other suggestions? Still exhibiting dame symptoms of overheating when driven at steady motorway speeds.
No overheating if thrashed hugely on back roads. ( many revs many gearshifts etc) Starting to wonder if there's an airflow issue (e.g all air stalled in engine bay at higher speeds) or something
Demetris
Well-Known Member
What i would do:
Verify the overheating with an independed thermometer (infrared or else).
Lean mixtures and retarded ignition promote overheat, so check that they are correct for your engine. Free flow exhausts and / or air filters cause the mixture to lean out. Standard needles are not good any more.
If i remember correctly you removed the engine driven fan and installed twin electric ones or something like that. Perhaps your installation is blocking airflow from the radiator where it is needed most. Motorway speeds. If you can make a try run without the electric fans fitted you will be able to verify this. When i fitted the A/C to my P6, the airflow loss from the installation of the condenser and the small electric fan in front of the radiator, made the car run hotter at motorway speeds, even with the A/C off. To compensate, i relocated the front number plate to help the airflow through the lower valance.
If everything turns out to be OK with the above and you still have the problem, i would suspect that something must be wrong with your new water pump. Unfortunately, sometimes even new parts, fail to perform according to the required specifications.
Verify the overheating with an independed thermometer (infrared or else).
Lean mixtures and retarded ignition promote overheat, so check that they are correct for your engine. Free flow exhausts and / or air filters cause the mixture to lean out. Standard needles are not good any more.
If i remember correctly you removed the engine driven fan and installed twin electric ones or something like that. Perhaps your installation is blocking airflow from the radiator where it is needed most. Motorway speeds. If you can make a try run without the electric fans fitted you will be able to verify this. When i fitted the A/C to my P6, the airflow loss from the installation of the condenser and the small electric fan in front of the radiator, made the car run hotter at motorway speeds, even with the A/C off. To compensate, i relocated the front number plate to help the airflow through the lower valance.
If everything turns out to be OK with the above and you still have the problem, i would suspect that something must be wrong with your new water pump. Unfortunately, sometimes even new parts, fail to perform according to the required specifications.
1396midget
Well-Known Member
Demetris said:
good plan, and next on my list.
Demetris said:
I've got KO needles in mine - a bit richer than standard to take care of the free flow filters and loss of one silencer. Simon BBC electronic dizzy that's been OK so far. Will give timing and mixture a go again (keeps me off the streets)
Demetris said:
Cheers, I'll give that a go. The problem started before I changed the fan mounts. Possibly turning them on at high speed might help? Can't remember if I built the fans so they could come off without taking the rad out...
Demetris said:
that would be sad, but not unexpected.Not sure whether I should float the HGF boat, or the slipped liner boat wither (my 3.5 is bigger - says +20 on it under the valley gasket...)
colnerov
Well-Known Member
Hi, that +20 could be the bores are plus 20 but I'm not sure that is common because it is easy
to measure them. However Ford used to mark the Essex blocks like that if the main bearings
were line bored out a further 20 thou to correct a fault, so you knew to get main bearing set
that were bigger on the outside diameter. Harvey would be able to say if Rover did the same.
Colin
to measure them. However Ford used to mark the Essex blocks like that if the main bearings
were line bored out a further 20 thou to correct a fault, so you knew to get main bearing set
that were bigger on the outside diameter. Harvey would be able to say if Rover did the same.
Colin
1396midget
Well-Known Member
Demetris
Well-Known Member
1396midget said:
It is actually the exhaust changes that you have introduced that might cause a problem at mid to high engine speeds. Unfortunately only on a rolling road you can find out what really happens. There is no point spending too much time adjusting the mixture strength at idle. Another way around this is to fit a wideband lamda sensor and go for a drive. I think that one or more of the forum members (Quattro?) has one fitted in his P6B.
1396midget said:
The problem is that the fan motors and brackets represent blanked out areas on the radiator core. Turning the fans on when travelling above say 60 mph will have no effect on these blanks, while the airflow speed is already naturally high. Modern cars that were fitted from the factory with electric fans, probably have already taken into account these blanks due to the fan itself and have a larger radiator area to compensate. As you understand this is not the case with our cars.
1396midget
Well-Known Member
Demetris said:
Yep, agree with all of that. Just seems strange that it's started doing this without any easily identifiable changes. The same issue has survived 2 radiators, 2 stats, 2 sets of hoses, 2 gearboxes and 2 different fan mounts. Timing hasn't changed, mixture has but has made no difference. It has ran fine with the same needles and the same fan arrangements.
Might be able to spend some time this weekend playing with it, hunt for coolant leaks (can't see any now), check out plugs etc. It can't be anything too serious; it goes so well.
One thing I've not tried is sitting it at 3000 rpm without going anywhere, though it's bound to overheat doing that!
It does rather point at the water pump
1396midget
Well-Known Member
symes said:
all flushed when I suspected the rad to be blocked, then again when I changed the rad.
ghce said:
Thanks, I'll try and find it!
BUT, we have an update!
after the thrashing it got the other day, it's fixed it.... so it appears to be fine now. I suspect an air lock that's finally worked it's way out?
more strangeness though, now that it appears to be OK, I've spotted a cause? - slight coolant leak from the rear of the offside bank on the valley gasket. bums. still, not a big job. Not lasted very long though - was just a cheap tin one.
1396midget
Well-Known Member
harveyp6 said:
I didn't. Will do now.
Presumably composite valley gasket won't go with non-composite head gasket? Is it another tin one I'll need or is there enough tolerance in the arrangement to fit the fatter comp one?
1396midget wrote,...
Ideally stay with a tin gasket. Apply hylomar or any other suitable sealand around the coolant passages, torque down the bolts, running from the centre outwards in a crisscross pattern.
Ron.
Ideally stay with a tin gasket. Apply hylomar or any other suitable sealand around the coolant passages, torque down the bolts, running from the centre outwards in a crisscross pattern.
Ron.